Method of tensioning and anchoring wire bundles for prestressed concrete structural elements



May 12, 1953 AL A. BLATON 2,637,395

METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES FOR PRESTRESSED CONCRETESTRUCTURAL ELEMENTS 4'7 .4 Sheets-Sheet 1 Filed Jan. 23, 19

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May 12, 1953 A BLATQN 2637,895

A. E. METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES F01 PRESTRESSEDCONCRETE STRUCTURAL ELEMENTS Filed Jan. 25, 1947 4 Sheets-Sheet 2 Arry y1953 A. E. A. BLATON 2,637,395

- METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES FOR PRESTRESSEDCONCRETE STRUCTURAL ELEMENTS Lled Jan. 25, 1947 4 Sheets-Sheet s A. E.A.

BLATON 2,637

s FOR 4 SheetsSheet 4 May 12, 1953 METHOD OF TENSIONING AND ANCHORINGWIRE BUNDLE PRESTRESSED CONCRETE STRUCTURAL ELEMENTS 1947 Filed Jan. 25

Arly) Patented May 12, 1953 TENS O AND I ANCHOBING WIRE-BUNDLES FOR-PRESTRESSED. .CON- CBETE STRUCTURAL ELEMENT Armand- Eugene-AdolpheElaton; Woluwe-Sainb Pierre, Brussels, Belgium,assignor of one-halftoxEniileiJules Lucien Blaton Bz'ussels Belgiumr Application January 23,1947;-Serial .N0 723/Z 18 In. B lsiumM r .2 1 .421.

Section 1, Public Law 690; "'August 8, 1946 Patent expires March 21',19627 6 Claims. (01. 251 -148).

The: nresen-txinvention relates.to.:.:a :meljhQdwofn producing; apredetermined tensile%stress:betweenu wosfixedpointsef aeonoreteg-structure -byimeans;

ofea tensionegi wire abundlezeonsisting:10f;a 11111-1 ralityggof-:,high.'tensilezstrength-metal wires ex-.1- tendin adjacentutouoneanother betweenvsaidi;

fixed m im.

The sprincipalriaobjeotg Oflifth iinventionuis to obylatethedifiiculties -whieh;heretoiorehavelbeen; eneeunteredima'theuuniiorm;:tensionini; or wire bundlesend particularlya-imthe uniiormitension inst0 "wirer lnundles 50f a :lengthexceecling.:sev-;

mtllfeetqiandz;:containing a sv-considera-blevnumben ofrindividualwires;

Another object "19f ltherimrentiomis togprov-ide a imethmi;whereby-seven, ima rmultiawire; bund-lez oft; great;lengthuanducontainings a -large number; suolrzas 2Q:erzunore-wwires xanrexactl-y mniform; nsionmetoir all theuinriividual wirescan-beleacomplished.

A,, stil 1ii;furthen; :objectwofmthe invention: is. to

nevrideia methodfonthe tensioning of m ultiewirez bundlesewhieh' bemarried: into rseiiect easily: and;iwith,%-sma11en ranch.less-rtexpensive tensioning machinery; than-.jhadhtqbelused:heretofore.

Still another object of the invention :istonpro-L videaa rmethmiuwhielrcanxbeuused .wvithout inc e sedardifficuities:regardless:of the vnumberof; Wires: iniathezbundlegso ,thatawire bundles contains A ingzagreatnumber: ofiwires-can he) employed anelzi niformly?tensionerhjust aseasily; as: WiIBibllllw-r dlesycontainingla small numbenoi wires. 5

GGHQ'IZfiHYwaGQOITdlngazto theupresenninvention,"

these objects are accomplished Joya-a methoclxcom-i prising :the; io1lowing-,.-steps:i

First:tlxemntensionedaviresforming thebundlei anenarrangedethroughouttheumain longitudinal l pq fliiqn-rofiaithe'agwire:bundle; which extendsbe weemtwoatransversewplaneslocated near the respfieechsubstaniell-yparalleltlayers each 1 inclurl-9: ing a ;;rplurality wofg closely,spaced substantially parallel wireszimsuch a mannenthat at any cross:section-lomsaiutmain portion.=.ofzthe Wire n l the wires aresubstantially uniformlyldistribute'd oventheentire: area of vthe crosssection. Then,

anethenthesame as=.in said main" portion of; thebundleiu Thengswapredetermin eol, tun "ln, l.l)'l"itudinal tensioning stress is exertedat the other' enduofuthe bundle-ona fraction otthe total'numbee of-wires: thebundle so as to tension one,

tw aor; 55 11541 numberzl fknwi ese such ass-f ur. W re :at .zone/utmei-iwh -le mainta nin a l: ether wires th ou hout said. main porti nt-t eb ndle in -their mutually spaced parallel positions.

Eaoh-tensioned wire is anchored at the 013,- posite end, of the: bu ni1e:i against t longitudinal, movement arelativel ,to the; rfixede1points of the. structure in a relative position i with, respect to the.other wires the sameasin said maim portion,

' of the undle, andv th t i ine; ndeanchorin steps-are repeated rwithrespeotto a small mim ber ofttheorder from onelto; founata time, ofithema ning; Wire f. h b ndle,untile lutheiw ese of th bu e av ben.:uniform1y. t nsion ci, and: chored:

Th invention. is p r icularl applicablet the;- anufac ure: of ar cles,su h.-asconeret b am e to which a certain pre-tension is to beimparteqi;

An ,eleme t'f r d tributing, the-W r s. i ;p1 ef-' ablya ho izontalonfsn pqseiifll e emay 3 .7;- or l s; uth spresen inventionbencunstitutem bysuperposed plates, Y which are 1 connected ito-e t r; f exam 1e y a t,ande h nf w ich is provided .with trapezoidal reeesses in; whiehjuhe,wires afterhavingv beenstretchedlcan bellockedl and anchored i forexample means) of. Wed-. now per se-e Numerous variationsin .thedes n oft ese e -i ments can naturally be conceived aqcording to the application envisaged without dep arting from the principles which form thebasis of--thevention.

The accompanyingdrawings show themanner in which the invention can:be-carried into'effeot: 1

Figure -l is a plan viewyand Figure 2 an elevation:of:thewholeeinstallationz serving to stretch theametaliwires:

ures 3,: .4 and 5 re: 1 C iQn cQH'J Q'T lQSF III--III, and,, V-,-.V,-;respectively 01?. Fig:- ure l v Figuresrfi :ancl-J? 'relate .to amodifieation which the wires are tension,ect=imzlividual,ly.r

Figures 8 to 13.,relateto,eertain modifications ofthe methodflaccordingtothe, invention and to, certain. details of t the structural elementswhich: may be usedin itsexecutionm InWFie re 1 0.v5, 1..ignates,.rqund,wiresm f r example. of s ee1,. ,f ermine. a wire, bundl nwhich a tensile force to be exerted; as is1shown" particularly in Figure3, according to the in-- vention, the wires I are disposed in the bundlein closelyadjacent horizontal parallel layers each including a pluralityof closelyspaced 'substan tially parallel wires The Various layers aremaintained attainstance from one another by the interposition ofhorizontal pins 5 which are inserted at intervals during the preparationof the cable so as to effect a preliminary grouping. Vertical pins 5 arealso provided in order to separate the wires. 2 is a thin metal envelopein the form of a truncated pyramid, which is provided at its extremitydirected towards the main portion of the wire bundle with a metal ring3, through which pass the wires I (Figure 3). The envelope 2 directs thewires towards a wire anchoring element 4, which may vary in designaccording to the purpose of the arrangement. Preferably, the wires l areenclosed in a sheath 2 of sheet iron connected to the ring 3. It will beunderstood that the wires in the main portion of the wire bundle whichextends to the left from the ring 3, as shown in Figures 1 and 2, forinstance, to a similar ring near the other end of the bundle (notshown), are arranged and maintained throughout in the positionsindicated by the cross section shown in Fig. 3, so that at any crosssection of said main portion of the wire bundle the wires aresubstantially uniformly distributed over the entire area of the crosssection. It will also be understood that the wires l are anchored at theother end of the bundle, for instance, in an anchoring element (notshown) corresponding substantially to the wire-anchoring element 4.

The wires I may be, for instance, steel wires 2 with a high elasticlimit. Wire bundles consisting of such steel wires are particularlysuitable for the reinforcement of concrete structures. Part of aconcrete block reinforced by a wire bundle tensioned according to thepresent invention is indicated by the reference numeral P in Fig. 1.However, the invention is not limited to this application.

In the examples shown in Figures 1 to 5, the wire anchoring element 4comprises a series of superposed metal plates 6 provided with recesses 1having a trapezoidal form in plan view and two locking plates 8 rigidlyconnecting all the plates 6 with the aid of bolts 9 (Figure 4). Betweenthe plates 6 provided with notches are interposed thin metal sheets lserving to avoid friction of the wires against one another when they areplaced under tension.

The traction device, which is shown by way of example in the right handpart of Figures 1 and 2, comprises a metal cross-piece H having on oneof its faces two recesses E2 of trapezoidal form and forming with tworods !3 and a crosspiece I 4 a coupling system permitting of exerting atractive force on the wires. The rods [3 form at their extremities forksi5 bearing against the cross pieces II and I4, and bolts l6 connect therods l3 to the cross-pieces H and M.

The cross-piece M bears against a traction device ll which may be ahydraulic jack or any other lifting apparatus.

A metal plate :8 having slots [9 for the passage of the rods [3 servesas a seat for a base supporting the traction device II. This plate I8 isin addition provided with securing members 2| for stays 22 connected toan annular plate 23 adapted to bear against the anchoring element 4.

The suspension of the jack I! may be effected with the aid of metalplates 25 reinforced by angle irons 26. These angle irons have apertures21 which may be brought into register with apertures 28 in the base 20.Pins 29 may be inserted into these apertures to secure the jack H atdifierent heights. During vertical adjustment of the jack ll the rods I3move vertically in the slots [9 of the plate 18. I,

As will be seen from Figure 4, owing to the design of the anchoringelement 4 which is formed by superposed plates having recesses therein,the wires, on leaving the envelope 2, are distributed in parallel,horizontal layers which, in the case illustrated, each comprise fourwires I penetrating in pairs into the recesses 1. Each layer couldcomprise a larger number of pairs of wires or only two wires. The numberof layers will depend upon the tensile force to be exerted.

In order to exert a tensile stress on the wires and to maintain thispull for as long as desired, the following procedure is adapted in thecase where it is desired to tension two wires at a time.

Two of the wires I passing through a recess 1 in the element 4 arebrought into a recess I! in the cross member H and are secured thereinby means of a key or wedge 36. The jack I1 is then set in operation, andthis jack, by exerting a thrust in the direction of the arrow on the=cross piece l4 moves the entire coupling systemand exerts on the pair ofwires secured in the cross piece II the pull to be produced. When theelongation of these two wires is such that it corresponds to the forcewhich it is desired to produce, the two wires l are keyed in the ele-'ment E in known manner by means of a wedge 3|, whereupon the jack I? isslackened and the wedge which has served to secure the two wires 1 tothe coupling system H, l3, i4 is removed. .The operation is repeated asmany times as there are pairs of wires in the bundle and it is thuspossible by multiplying the number of wires to obtain a total tensileforce of any desired strength as shown in Fig. 1, up to 4 wires may betensioned simultaneously.

When all the wires of the bundle have been placed under tension, thecoupling system II|3I4 is removed, as also the members |82223, and thetensile force will be main.

tained in the wires as long as the wedges 3| are left in position.

If it is desired to remove the tensile force in the wires 1, thecoupling system is replaced in position and a further pull is exerted oneach pair of wires until the keys or wedges 31 can readily be removed.The device employed for applying the tensile force is slackened, thewedges 3B are removed and the various pairs of wires are released.

Instead of measuring the tensile force to be;

produced in wires by calculating their elongation,

it is possible to insert between the coupling system and the device fortensioning the wires, a.

dynamometer indicating at each instant, the intensity of the tensileforce produced. A manometer indicating the pressure obtained in the jacking one another and they also permit that when the tensile force isexerted on some of the Wires this arrangement be maintained and thatnone of the wires which are tensioned become wedged between wires whichare not tensioned.

In the embodiment shown in Figures 1 to 5, it

has been assumed that the tensile force has been.

applied to two wires or to four wires at a time.

L to 4 at a time while maintaining all the wires throughout said mainportion of the bundle in their mutually spaced, parallel positions,anchoring each tensioned wire at said opposite end of the bundle againstlongitudinal movement in the direction toward said first end of thebundle in a relative position of said wire with respect to the otherwires the same as in said main portion of the bundle, and repeating thetensioning and anchoring steps with respect to a small number of theorder of 1 to 4 at a time of the remaining wires of the bundle until allthe wires of the bundle have been uniformly tensioned and anchored.

2. In the manufacture of load-carrying structural concrete elementspre-stressed to a high tension by means of at least one bundle of hightensile strength metal wires which extend closely adjacent to oneanother in a longitudinal cavity of the structural element and cooperateto form a single unit for the maintenance of the desired high tension inthe structural element, a method of forming the wire bundle andimparting thereto the desired high tension, said method comprising thesteps of arranging .a plurality of untensioned high tensile strengthwires to extend, throughout the main longitudinal portion of the wirebundle formed by said wires between two transverse planes located nearthe respective ends of the bundle, in several closely spacedsubstantially parallel layers, each including a plurality of closelyspaced substantially parallel wires in such a manner that, at anycross-section of said main portion of the wire bundle, the wires aresubstantially uniformly distributed over the entire area ofsuchcross-section, anchoring the wires at one end of the bundle againstlongitudinal movement in the direction toward the other end of thebundle in relative positions of the several wires with respect to oneanother the same as in said main portion of the bundle, exerting at theother end of the bundle a predetermined, uniform, longitudinaltensioning stress on a fraction of the total number of wires in thebundle so as to tension a small number of wires of the order from 1 to 4at a time while maintaining all the wires throughout said main portionof the bundle in their mutually spaced, parallel positions, anchoringeach tensioned wire at said opposite end of the bundle againstlongitudinal movement in the direction toward said first end of thebundle in a relative position of said wire with respect to the otherwires the same as in said main portion of the bundle, and

repeating the tensioning and anchoring steps I with respect to a smallnumber of the order of 1 to 4 at a time of the remaining wires of thebundle until all the wires ofthe bundle have been uniformly tensionedand anchored.

3. In the manufacture of load-carrying struc- 300 tural concreteelements pre-stressed to a high tension by at least one bundle of hightensile strength metal wires which extend closely adjacent to oneanother in a longitudinal cavityof the structural element and cooperateto form a-single unit for the maintenance of the desired high tension inthe structural element, a method of forming the wire bundle andimparting thereto the desired high tension, said methodlongitudinalmovement in "the direction toward the other end of the structuralelement in relative positions of the several wires with respect to oneanother the same as in said main portion of the bundle, exerting at theother end of the bundle a predetermined, uniform, longitudinaltensioning stress on a fraction of the total number of wires in thebundle so as to tension a small number of wires of the order from 1 to 4at a time while maintaining all the wires throughout said main portionof the bundle in their mutually spaced, parallel positions, anchoringeach tensioned wire at the opposite end of the structural concreteelement against longitudinal movement relative to the structural elementin a relative position of said wire with respect to the other wires thesame as in said main portion of the bundle, and repeating the tensioningand anchoring steps with respect to a small number of the order of 1 to4 at a time of the remaining wires of the-bundle until all the wires of.the bundle have been uniformly tensioned and anchored.

. 4.; In. the manufacture of load-carrying structural concrete elementspre-stressed to a high tension bymeans of at leastone bundle of hightensile strength metal wireswhichcooperate to form a single .unit forthe maintenance of the desired high tension in the structural element,a. method of formingrthe wire bundle and impartingthereto the desiredhigh tension, said.

method comprising the steps of arranging a pluralityof untensioned.high. tensile strength wires to. extend throughout the main longitudinalportion of the wire bundle formed by such-wires between two transverseplanes located near the respective ends of the bundle, in severalclosely' spaced substantially parallel layers each including a pluralityof closely spaced substantially parallel wires in such a manner that, atany cross-section of said main portion of the wire bundle. the wires aresubstantially uniformly distributed over the entire area of suchcrosssectionanchoring the wires at one end of the bundle againstlongitudinal movement in the direction toward the other end of thebundle in relative positions of the several wires with respect to oneanother the same as in said'main' portion of the'bundle, guiding thewires from theend of the main portion of the bundle near the oppositeend of the latter through a transverse anchoring plane located betweensaid end 'of said main portion and said opposite end of the bundle alongdiverging lines to define animaginary truncatedv pyramid having itssmaller base at the end of the main portion of the bundle and its largerbase in said anchoring plane, the wires being located in said anchoringplane in relative positions the same as in the main portion of thebundle with the spacing between adjacent wires in the anchoring planebeing considerably greater than the spacing between the same wires inthe main portion of the bundle, exerting at the other end of the bundlea predetermined, uniform, longitudinal tensioning stress ona fraction ofthe total number of wires in the $59 bundlesso as to tension afr'sniallnumber iof wires bfthe orderfrom llto 4 at a tim'e izzhileomaint'ainngan the: wires throughouiasaid mainuportion tithe bundleintheirmutually-rspaced-sparallel wpositions, anchor-ingeach tensionedwirevin said 'eianchoring plane-against longitudinal "movement 'in thed-ircctiontoward saidfirst ehdw bf xthe fibundle in a relative-positionof saiid wiretvlthnespect to the other'wires the-sam as in said mainportion of the bundle, and repeating the tensioning andanchoring'st'eps' with respect-rte" a wsniallnumberof 'theorder of lto 4at atime of "s'the remainingwiresofthe 'buifdle ufitildll the wires'bfthe bundle havedoeenmniforirfly tensioned and anchored.

5. In the manufacture of load-carrying structural concrete elementspre-stressed to a high tension by means of at least one bundle of hightensile strength metal wires which extend closely adjacent to oneanother in a longitudinal cavity of the structural. element andcooperate to form a single unit for the maintenance of the desired hightension in the structural element, a method of forming the wire bundleand impart ing thereto the desired high tension, said method comprisingthe steps of arranging a plurality of untensionecl high tensile strengthwires to extend, throughout the main longitudinal portion of the wirebundle formed by said wires between two transverse planes located nearthe respective ends of the bundle, in several closely spacedsubstantially parallel layers, each including a plurality of closelyspaced substantially parallel wires in such a manner that, at anycross-section of said main portion of the wire bundle, the wires aresubstantially uniformly distributed over the entire area of suchcross-section, anchoring the wires at one end of the bundle againstlongitudinal movement in the direction toward the other end of thebundle in relative positions of the several wires with respect to oneanother the same as in said main portion of the bundle, guiding thewires from the end of the main portion of the bundle near the oppositeend of the latter through a transverse anchoring plane located betweensaid end of said main portion and said opposite end of the bundle alongdiverging linesto define an imaginary truncated pyramid having itssmaller base at the end of the main portion of the bundle and its largerbase in said anchoring plane, the wires being located in said anchoringplane in relative positions the same as in the main portion of thebundle with the spacing between adjacent wires in the anchoring planebeing considerably greater than the spacing between the same wires inthe main portion of the bundle, exerting at the other end of the bundlea predetermined, uniform, longitudinal tensioning stress on a fractionof the total number of Wires in the bundle so as to tension a smallnumber of wires of the order from 1 to 4 at a time while maintaining allthe wires throughout said main portion of the bundle in their mutuallyspaced, parallel positions, anchoring each tensioned wire in saidanchoring plane against longitudinal movement in the direction towardsaid first end of the bundle in a relative position of said wire withrespect to the other wires the same as in said main portion of thebundle, and repeating the tensioning and anchoring steps with therespect to a small number of the order of 1 to 4 at a time of theremaining wires of the bundle until all the wires of the bundle havebeen uniformly tensioned and anchored.

6. In the manufacture of load-carrying struc- 20i .1 thewstructuralelement and cooperate-.- to

-.i.tor1m a's'mgle unit for thesmaintenance oflthe :rlesired hightension in thesstructural(element, raimethodsof forming thelhirabundlewand imrpartins thereto the desiredlhigh tension saidimethodtcomprising the stepsanf arranging a apluralitysofz high tensilest-rength metal-swims: in

. alongitudina1 cavity leftin apre-castconcrete element uto extend,throughout. ithe imainslonigitudinal portion of'the wire'bundle.tormedvby said wires between two transverse planes located near therespective ends of the bundle, in several closely spaced substantiallyparallel layers each including a plurality of closely spacedsubstantially parallel wires in such a manner that, at any cross-sectionof said main portion of the wire bundle, the wires are substantiallyuniformly distributed over the entire area of such crosssection,anchoring the wires at one end of the hardened structural concreteelement against 1ongitudinal movement in the direction toward the otherend of the structural element in relative positions of the several wireswith respect to one another the same as in said main portion of thebundle, guiding the wires from the end of the main portion of the bundlenear the opposite end of the structural concrete element through atransverse anchoring plane located substantially at said opposite end ofsaid structural element along diverging lines to define an imaginarytruncated pyramid having its smaller base at the end of the main portionof the bundle and its larger base in said anchoring plane, the wiresbeing located in said anchoring plane in relative positions the same asin the main portion of the bundle with the spacing between adjacentwires in the anchoring plane being considerably greater than the spacingbetween the same wires in the main portion of the bundle, exerting atthe other end of the bundle a predetermined, uniform, longitudinaltensioning stress on a fraction of the total number of wires in thebundle so as to tension a small number of wires of the order from 1 to 4at a time while maintaining all the wires throughout said main portionof the bundle in their mutually spaced, parallel positions, anchoringeach tensioned wire in said anchoring plane at the opposite end of thestructural concrete element against longitudinal movement relative tothe structural element in a relative position of said wire with respectto the other wires the same as in said main portion of the bundle, andrepeating the tensioning and anchoring steps with respect to a smallnumber of the order of 1 to 4 at a time of the remaining wires of thebundle until all the wires of the bundle have been uniformly tensionedand anchored.

.ARMAND EUGE NE ADOLPHE BLATON.

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